An understanding of microtubule assembly/disassembly dynamics is sought that would explain spindle formation and certain aspects of chromosome movement. Combined micromanipulation and molecular experiment on both living and lysed cells would be used to modify microtubule assembly/disassembly and to test simple models of spindle form and function. Chromosome movement during prophase would also be studied -- as a model system where movement occurs without the direct involvement of microtubules. Earlier studies of experimentally controlled chromosome distribution suggested possible molecular mechanisms that would be tested by proposed in vitro studies of isolated chromosomes and microtubule subunits. Studies of lysed cells would be used in an attempt to understand the fundamental difference between meiosis and mitosis that leads to the reduction number in meiosis.